Refrigerant Pressure Sensor / Switch: Description and Operation

PURPOSE
The Air Conditioning Cycling Switch (ACCS) provides input to the Powertrain Control Module (PCM) and the Variable Control Relay Module (VCRM) to control clutch cycling.

OPERATION
This switch closes at 45 psi (increasing pressure) and opens at 24.5 psi (decreasing pressure), which provides an input signal to the PCM and the VCRM to control clutch cycling.

Clutch cycling controls the evaporator core pressure at a point where the plate/fin surface temperature is maintained slightly above freezing, preventing evaporator icing and blockage of air flow.